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Range indication 21"vs19" wheels

Range indication 21"vs19" wheels

Submitted by davecolene0606 on October 19, 2012

Wondering out loud if the S is programmed for the specific wheel. I have been under the impression that the 19" wheel get a slight range advantage and so I wonder if that affects the vehicle projected range calc.

Anyone know?

Brian H |
October 19, 2012

Well, the car extrapolates your last 30 miles, so it will show up there.

bgoodwin |
October 19, 2012

I did suggest to Tesla to add that feature. I'm consistently 5-10% under Rated range .. .and while I can use projected, the "rated" range doesn't mean what it's "supposed" to mean. If I knew rated meant that's what I'd get in ideal conditions at 65 MPH, then I know I could immediately adjust my driving to attain that range. However, that's not true (I have to remember it'll be 5-10% less than that).

danielccc |
October 19, 2012

The 21" wheels have low-profile tires. The actual tire diameter should be the same or very close.

This is why the 19" wheels have been reported to be quieter; the tire sidewall is 1" taller and the tire is not so stiff.

Tomas |
October 19, 2012

I would think that the range estimator would not be affected by the wheel size for the simple reason that it is tied into the speedometer. The same issue that you bring up would also relate to the speedometer. If the outside diameter of the 21" wheel with the tire is larger than the outside diameter of the 19" wheel plus the tire, then a car with the 21" wheel car would actually be going faster than the 19" wheel car (if the speedometer where calibrated for the 19" wheel). My guess is that they don't have to calibrate the speedometer to the wheel size because the outer diameter is the same for both wheels. The tire thickness is 1" wider on the tire on the 19" wheel than the tire in the 21" wheel. One inch wider on both sides of the tire would add two inches to the diameter making up for the two inches fewer in the 19" wheel.

jkirkebo |
October 19, 2012

The wheels are virtually the same size, range has nothing to do with the size. THe 21" gets less range because LRR tires are not available in 21" sizes.

LRR = Low Rolling Resistance

Maybe a software update should let people put in a "fudge factor" to correct rated miles ? So if you always get 10% less, put in 0.9 and the rated miles are always multiplied by 0.9 ?

Brian H |
October 19, 2012

Yes, I don't think he was asking about the geometry, but the rolling resistance or other characteristics of the 19" affecting range. Since the 21" benefit is added traction, increased r-resistance would seem to be a necessary corollary.

Volker.Berlin |
October 20, 2012

Since the 21" benefit is added traction, increased r-resistance would seem to be a necessary corollary. (Brian H)

Right. However, LRR tires today have much better performance than LRR tires of five years ago. However, performance of performance tires has increased as well, so the gap is still there but the bar is higher.